Sostenuto piano



. Aug. 4, 1931. I s, 50p 1,817,507

sosrsmo PIANO Filed April 14 1928 Patented Aug. 4, 1931 P NT OFFICE sac-MON warm o BROOKLYN, new :YQRK

sos rmv H O Application filed pril 14, 1928. Serial 1W0. 269,968.

This invention relates to electrical sostenuto pianos and has special reference-to a sostenuto piano of the general type descr bed in the U. S Letters Patent granted to me a; and bearing the number 1,598,056, in that electro-magne-tic means are employed for'obtaining the sostenuto effect and these means are controlled intheir action by a current pulsator which is in turn controlled by the 1%" vibrations of the piano string, it being .un-

derstood that I here refer to a -singleunit of the complete apparatus since each-note on the piano will have its stringer strings controlled for sostenuto effect in like manner.

In the study of true sostenuto action by means of electro-magnetic control *I have encountered various complexities due to the physical laws pertaining to the result desired to be accomplished and a brief ex- Co planation of the action of the several physical forces in 'the'solution of thisproblem will make clear the value and utility of the present invention. I

It is not practically possible to set-a string into musical vibration while undersuchtension as exists in an ordinary pianoby merely pluckingat the stringby electro-magnetic attraction. A vibrating string may, howv ever, have its vibrations prolon ed or main- 1 L tainedby properly arranging or magnetic attraction of thestring at a definite phase in its vibration and in order to do this it is essential that the plucking or attraction of H the string be in synchronism with the mo- 3 tion of the string at .the particular zone where the pluckingor attraction is applied.

Furthermore, the piano string to give full musical value by its vibrations must assume the loops and nodes not only to sound its fundamental note but also to sound the partial tones or over tones which render the note agreeable and give it its proper character. These partial tones or over tones are generated by reason of the imposition of smaller loops and nodes upon the fundamental loops of the piano'string. It can now be realized that the pluck onthe string must be in exact relation to the motion of thestring when the'pluck is applied and also that the pluck or attractionmust occur when the particular portion ofthe string attracted is approaching the electro-magnet andonly for that lesser portion of theperiod that vthe superimposed or over tone loop at that particular point is also approaching the magnet.

To achieve such result by absolute timing or other control of the electriccurrent energizing the attracting magnet :by extraneous means is impractical but by a proper assemblage of operating elements and by havingdueregard to .theproperties of materials such synchronism of the magnetic pluck maybe controlled in a feasible ,mannor by the motionfand position ofthe string itself and the device disclosed in vthe present application and whichhas given satisfactory service ,may (bedescribed in general as :follows:

Sincevthe force of gravity is constant and not affected by change ,in.-the properties ,of materials, I have usedthis force as the major factor in the means of attaining synchronism of magnetic pluck through the motion of the musical string itself and in the present application of the invention there has beendisclosed a pair of electrodes which are mounted in a circuit includinga source of electric energy, a switch controlled by the piano key governingthe respective note and an electro-magtnet disposed close tothe string or strings generating the note when vibrated. One of these electrodes rests by reason of its Weight upon a bed of granular conducting material, this material in turn resting upon the other electrode which is fastened to a supportof low resiliency so that the circuit has a highdegree of inertia as compared to the velocity of motion attained by the musical string in sounding the tone. This circuitis put in motion by means ofta connection between the circuit and the musical string which composed of a material which, while resilient to the desired extent, has a total stretch less than the range of motion of the vibrating musical string. It is also to be] observed that the force of gravity acting on the free electrode cannot overcomeits inertia rapidly enough to impart velocity equal tothat of the musi cal string when in motion since the distance through which the upper electrode tends to travel is very minute, being only equal to the amplitude of vibration of the string atthe point to which connection is made. Uilherefore, since the force of gravity cannot impart velocity to the electrode equal to that of the musical string when in motion, we have a chain of connections between the high velocity motion of the musical string and the electric contact between the free electrode and the bed of granular conducting material on which it rests and there results a variation in the conductivity of the circuit. It is now" merely necessary to adjust the parts so that the phase of the variations in this circuit are synchronous with the phase of vibration of that portion of the musical string w iieh is affected by the magnetic pluck in order to attain musical sostenuto effect.

l ith the above and other objects in view as will be hereinafter apparent, the inven tion consists in general of certain novel details of construction and combinations of parts hereinafter fully described, illustrated in the accompanying drawings and specifically claimed.

In the accompanying drawings like characters of reference indicate like parts in the several views, and: 2

Figure 1 is a diagrammatic view illustrating one form of the arrangement of the circuit, actuating magnet and controlling pulsator in their relation to a piano string.

Figure 2 is an enlarged detail side elevation of the pulsator showing its relation to a piano string.

Figure 3 is a section on the line 33 of Figure 2.

Figure 4 is an enlarged detail elevation of the upper or free electrode of the pulsator.

In the arrangement shown in Figure 1 the parts are illustrated in a purely conventional manner and various parts are omitted as not being necessary to an understanding of the invention. In this figure a piano string is supported in the conventional way on bridges 11 and 12 and beneath this string a hammer I-I actuated from the key 1'7, the connection between the hammer and key being omitted as being of the usual conventional variety and forming no specific part of the present invention. An electro-magnet 13 fixed in proximity to the string and as near to the zone where the piano hammer H strikes as is found practicable. From the magnet 13 a conductor wire extends to and is connected with the fixed electrode 21 of the pulsator indicated in general at 14. The magnet is also connected by a wire or conductor with one terminal of a suitable source of electric energy here indicated by a battery 15. From the battery 15 a wire 31 leads to one of the contacts of a switch 16 which is disposed beneath the key 17 so that depression of the key closes the switch. The other contact of this switch is connected to the loose terminal or electrode of the pulsator by a wire 30. The electrode or terminal 21 is fixed on a strip or blade 19 of insulating material and having a suitable degree of resiliency. In order to thus secure the electrode a stud 20 is screwed into the electrode or terminal 21 passes through the blade 19 and has screwed thereon a nut 29 which thus holds the parts together. This blade 19 has one end mounted on a suitable fixed part 32 of the piano so that vibration of the blade may be effected by a loop 18 extending from the free portion of the blade and passing around one or more of the strings 10 which are struck by the hammer II, it being well known that in some instances the note is produced by a single string while in other instances the required note is produced by a plurality of strings tuned in unison. Mounted on the terminal 21 is an insulating casing or cylinder 33 and supported on the terminal 21 within the cylinder is a bed of granular conductive ma terial 22 whereon rests the terminal 23 to which the wire is connected. This terminal 23 is in the form of a metallic sphere and has an equatorial groove 26 wherein is seated an elastic band 27, the parts being so positioned that the terminal rests on the bed 22 centrally of the bed, being held from moving into contact with the wall of the cylinder 33 by means of the band 27 while at the same time being free to move in the cylinder or casing without undue friction. The wire 30 has its end extending into a polar opening or bore 28 and as this wire comes down from above the pnlsator its tendency is to maintain the terminal 23 with its equatorial groove in horizontal position.

In the operation when the string 10 is caused to vibrate because of the hammer stroke such vibrations will be communicated to the loop 18 which is composed of wool yarn or silk thread and this will cause the blade or strip 19 extending from the rigid support located in the piano to vibrate. This strip 19 is preferably made of celluloid or other like material and is of such proportions that its return of vibration is less than that of the string 10. Now since the electrode or terminal 28 rests on the conducting material 22 the vibrations of the blade, due to the inertia of the terminal or electrode 23, have the effect of alternately compressing and decompressing the granular material and thereby alter the effective conductivity of such granular material between the terminals or electrodes 21 and 23 so that pulsations are caused in the electric circuit and the magnetic field due to the electro-magnet 13 is alternately increased and decreased in accordance with the increase and decrease of the effective conductivity of the granular material.

It will be noted in Figure 2 that three piano stringsiare depicted and it is well of double string and the remaining notes are-composed oftriplestrings. The loop 18 can be attached to one of the stringsof the note or looped around twoor three strings, the purpose for thisioop being :to convey vibrations to the blade19.

The free electrode23 functions best when there is no restraining force 'upon it and for that :reason it is made of a smaller diameter than that of the v-pulsator 14, but in some instances it has a :tendency to contact with the said Wall and this results in. a unsatisfactory musical =tone or foreign sound resulting of the impact of the electrode upon the wall. This is overcome by the application of the flexible ring 27, which also serves to maintain the sphere in a central position. The spherical shape of the electro'de -28 permits it toassume a natural position upon the bed of granular material 22 and in the event of its shifting from a central position or itsaxis shifting from the vertical the same area and the same pressure between it and the granular material is maintained.

VVhen'the apparatus is installed-as .indicated by the above description synchronism between pulsations or undulations of the electric current energizing the electro-magnet and the motion of the-string is accomplished by moving theloop 18 along the string untilsuch synehronism is obtained. As the loop contacts with the string. near one of its bridge supports, and preferably;

with the bridge near the strikingend-of the string, the loop needs to -be moved over only a slight distance to determine point for attaining synchronism with the musical vibrations of the string.

There has thus been provided a simple and eflicient device of the kind described and for the purpose specified.

It is obvious that minor changes may be made in the form and construction of the invention without departing from the material spirit thereof. It is; not, therefore, desired to confine the invention to the-exact form herein shown and described, but it is'desired to include all such as properly come within the scope-claimed.

Having thus described the invention, what is claimed as new, is:

1. In an electric-sostenuto -pian0,a piano string, a source of electric energy,an electro-magnet disposed close to the piano string in circuit with 'the'source of electric energy, a current-varying unit in series with the source of energy and'electro-magnet,said

unit comprising a lower and an upper electrode and comminuted conducting material confined between them, and means controlled by ithe vibration of the string and connecting the string and unitto actuate the latter as the string vvibrates, said means beiugcomposed of .a material of low resilieney.

2. In an electric sostenuto.,piano,a piano string, a source of electricenergy, an electroanagnet disposed close to the piano string i-ncircuit with the source of'electric energy, a current varying unit in series with the source of energiy and electro-magnet, said unit comprisingalower and an upper electrode and eomminuted conducting material confined betweenthem, means controlled by the vibration of the string and connecting the string and unit to actuate the latter as'the spring vibrates, said meansbeing composed of a material of low resiliency, and a vibratile support for said =unit having a periodicity of vibration less than that of the piano string.

3. In an electric sostenuto piano, a piano string, a sou-rceof electric ener an electromagnet disposed close to "the piano string in circuit with the so'urce'of electric energy, -a current-varying unit-inseries with the source of energy and electro-magnet, means controlledby'the vibration of the-string andconneeting thestring and unit to actuate the latter as the string vibrates, said means being composed of-a material oflow resiliency, and a vibratile blade supporting said unit and having one end fixed, said blade having a periodicity of vibration less th-an'that of the piano string. 7

4. In anelectric sostenuto piano, a piano string, a-source of electric energy, an electro magnet' disposed close to the piano string in circuit with the source of, electric energy, a current varying unit in series with the sourceof .energyand electro-magnet, and means controlled by the vibration of the string andconnectingthe string and unit to actuatethelatter as the string vibrates, said current bearing unit including a pair of I terminals, one of which isfree for movement solely underthe action of gravitation. 5. In an electric sostenuto piano, a piano string, a source of electric energy, an electromagnet disposed close'to the piano string in circuit with the source of electric energy, a

current varying unit in series with the source of energy and e'lectro-magnet, and means controlled by the vibration of the string and connectingthe string and unit to actuate the latter as thestring vibrates, said current bearing unit including a pair of terminals, one of which is free for movement solely under the action of gravitation, said free terminal resting normally on conductive material and being :so-constructedthat alteration of-its position relativeto such material about any axis of the terminal will not alter the conductivity of the electric current.

6. In an electric sostenuto piano, a piano string, a source of electric energy, an electro-magnet disposed close to the piano string in circuit with the source of electric energy, a current varying unit in series with the source of energy and electro-magnet, and means controlled by the vibration of the string and connecting the string and unit to actuate the latter as the string vibrates, said current bearing unit including a pair of terminals, one of which is free for movementsolely under the action of gravitation, said free terminal resting normally on conductive material and being so constructed that alteration of its position relative to such material about any axis of the terminal will not alter the conductivity of the electric current, said tree terminal presenting in all positions the same area to the medium upon which it rests.

7. In an electric sostenuto piano, a piano string, a source of electric energy, an electromagnet disposed close to the piano string in circuit with the source of electric energy, a current varying unit in series with the source of energy and electro-magnet, and means controlled by the vibration of the string and connecting the string and unit to actuate the latter as the string vibrates, said means being shiftable longitudinally of the string whereby to obtain synchronism of the variations in the magnetic attraction for the string and the motion of said string.

8. In an electric sostenuto piano, a piano string, a source of electric energy, an electro-magnet disposed close to the piano string in circuit with the source or" electric energy,

- a current varying unit in series with the source of energy and electro-magnet, said unit comprising lower and an upper electrode and connninuted conducting material confined between them, and means controlled by the vibration of the string and connecting the string and unit to actuate the latter as the string vibrates, said means having a low degree of elasticity.

9. In an electric sostenuto piano, a piano string, a source of electric energy, an electromagnet disposed close to the piano string in circuit with the source of electric energy, a current varying unit in series with the source of energy and electro-magnet, said unit comprising a lower and an upper electrode and comminuted conducting material confined between them, and means controlled by the vibration of the string and connecting the string and unit to actuate the latter as the string vibrates, said means having a low de ree of elasticity whereby to dampen the transmission oi the string vibrations to the current bearing unit.

10. In an electric sostenuto piano, a piano string, a source of electric energy, an electromagnet disposed close to the piano string in circuit with the source of electric energy, a current varying unit in series with the source of energy and electromagnet, said unit comprising a lower and an upper electrode and comminuted conducting material confined between them, and means controlled by the vibration of the string and connecting the string and unit to actuate the latter as the string vibrates, said means having a low degree of elasticity whereby to absorb part of the vibration of the string.

11. In an electric sostenuto piano, a piano string, a source oi electric energy, an electromagnet disposed close to the piano string in circuit with the source of electric energy, a. current varying unit in series with the source of energy and electro-magnet, and means controlled by the vibration of the string and connecting the string and unit to actuate the latter as the string vibrates, said means functioning at a lesser period of vibration than the period of vibration of the piano string.

12. In an electric sostenuto piano, a piano string, a source of electric energy, an electroniagnet disposed close to the piano string in circuit with the source of electric energy, a current varying unit in series with the source of energy and electro-magnet, and means controlled by the vibration of the string and connecting the string and unit to actuate the latter as the string vibrates, said unit including a pair of terminals and a bed of conductive granular material carried by one terminal and having the remaining terminal resting thereon by gravity.

13. In an electric sostenuto piano, a piano string, a source of electric energy, an electro-magnet disposed close to the piano string in circuit with the source of electric energ a current varying unit in series with the source of energy and electro-inagnct, and means controlled by the vibration of the string and connecting the string and unit to actuate the latter as the string vibrates, said unit including a pair of teri'ninals and a bed of conductive granular material carried by one terminal and having the remaining terminal restin thereon by gravity, said means connecting the string with the lower terminal whereby the circuit conductivity is varied by the inertia of the upper terminal.

14. A pulsator for use in sostenuto pianos and the like in combination with a vibratory string, comprising a support capable of moderate but substantial vibratory movement and non-synchronously-resonant with the string, a lower electrode thereon, an upper electrode, means retaining the upper electrode for vibratory movement under inertia, and comminuted conducting material between the electrodes.

15. A pulsator for use in sostenuto pianos and the like in combination with a vibratory string, comprising a support capable of moderate but substantial vibratory movement and non-synchronously resonant with the string, a lower electrode thereon, a guide sleeve extending up from the electrode, comminuted conducting material retained by the sleeve upon the electrode, and a second electrode retained by the sleeve with clearcomminuted conducting material between the electrodes, and yieldable means between the upper electrode and its retainin means and preventing rattling contact etween them.

17. A pulsator for use in sostenuto pianos and the like in combination with a vibratory string, comprising a support capable of moderate but substantial vibratory movement and non-synchronously resonant with the string, a lower electrode thereon, a guide sleeve extending up from the electrode, comminuted conducting material retained by the sleeve upon the electrode, a second electrode retained by the sleeve with clearance for vibratory movement under inertia and resting on the comminuted material, and yield able means between the second electrode and the sleeve and preventing rattling contact between them.

18. A pulsator for use in sostenuto pianos and the like in combination with a vibratory string, comprising a support capable of moderate but substantial vibratory movement and non-synchronously resonant with the string, a lower electrode thereon, an upper electrode, means retaining the upper electrode for vibratory movement under inertia, and comminuted conducting material between the electrodes, the upper electrode being substantially spherical and having a shallow lower segment imbedded in the com minuted material affording current flow variations by lateral movement of said electrode.

19. A pulsator for use in sostenuto pianos and the like in combination with a vibratory string, comprising a support capable of moderate but substantial vibratory movement and non-synchronously resonant with the string, a lower electrode thereon, a guide sleeve extending up from the electrode, comminuted conducting material retained by the sleeve upon the electrode, and a second electrode retained by the sleeve with clearance for vibratory movement under inertia and resting on the comminuted material, the second electrode being substantially spherical and having a shallow lower segment imbedded in the comminuted material affording current flow variations by lateral movement of said electrode.

In testimony whereof I afiix my signature.

SIMON COOPER. 

